Fuels currently used for diesel engines contain components mainly from crude oil.
Natural gas and dimethyl ether are used as an alternative fuel for diesel engines. The main weakness of such fuels is their poor compatibility with oil diesel, since under normal conditions it generates gases. Furthermore, to operate the vehicle on these alternative fuels it is required its modification. (Dimethyl ether—Wikipedia).
There is a need in high-quality fuel composition for diesel engines containing components of biological origin, and also meeting requirements to diesel fuels quality when operating under any temperature conditions. Moreover, fuel should be environmentally safe. Currently, the most common component of biological origin in the fuels is rapeseed methyl ester, or RME (RU 2393209).
RME weak point is its high viscosity and high pour point, making impossible to use it at sub-zero temperatures. A by-product of RME is glycerin, which can cause some problem in case of a large product output. Esters from other vegetable oils and fatty acid methyl esters can be produced similarly, generally known as FAME (fatty acid methyl ester). Such FAMEs can be used for the same applications as the rapeseed methyl ester, but they also have a negative impact on the diesel fuel quality, particularly on its performance at low temperatures, and furthermore, their use in fuels increases nitrogen oxides emissions. In some cases, FAMEs and RMEs cause higher emission of particles and smoke generation at cold start.
WO 2001012581 (year) application describes a method of methyl esters production used as biological diesel fuel, based on which mixtures of fatty acids and triglycerides are esterified in a single phase. According to this method, a solution from fatty acids, triglycerides, alcohol, acid catalyst and co-solvents is produced at a temperature below the solution boiling point. Co-solvent shall be used in amounts to ensure a single phase, and then solution is allowed to stand for a time sufficient for acid-catalyzed esterification of fatty acids. Thereafter, the acid catalyst is neutralized, alkaline catalyst is added for triglycerides transesterification, and finally esters are thrown out from solution. By doing so, it is possible to obtain biofuel containing esters with glycerin content at least 0.4 wt. %.
The weak point is the process complexity and multi-stage nature, and high product cost.
The most similar to claimed invention is U.S. Pat. No. 6,013,114 patent (taken as a prototype). The fuel with vegetable oil and acetals components is proposed with flashpoint more than +550 C (see clause 5 of the formula).
The disadvantage of this invention is the high product cost. Alcohols (butanol) and higher, which are very expensive, are the raw materials for proposed acetals. Therefore, acetals derived from these alcohols, will also have a high cost. Formals based on C4 alcohols and higher have relatively high viscosity and pour point, and in mixture with vegetable oils cannot be used at low temperatures. Moreover, acetals described in the patent do not relate to renewable bio-products, therefore increase the level of greenhouse gases emissions into the atmosphere.
The object of invention is to develop alternative biofuel not containing oil component, but having a high cetane number, which, along with improved diesel fuel low-temperature and startup properties, inhibits corrosion, is used without engine modification and has an eco-friendly exhaust.
The technical result of invention is combustion process improvement in the engine operation, engine power increase and startup time reduction. In addition, this product can be used to reduce harmful engine emissions along with significant cost reduction by using components based on low-cost large tonnage products available provided with the domestic raw materials, including renewable ones, cold flow performance improvement and cetane number increase.
Said effect can be achieved by the biofuel containing dietilformal 40-80 by vol. % and glycerides of unsaturated fatty acids 20-60 by vol. %. Any vegetable oils are used as glycerides of unsaturated fatty acids.
Dietilformal used can increase diesel fuel cetane number to 60 points. Bioethanol (raw materials of lower cost) is a raw material for dietilformal synthesis, allowing to reduce the products cost.
In addition, dietilformal physical and chemical parameters exceed dibutilformal, allowing to produce biodiesel fuel with a pour point lower than −600 C.